摘要:

This paper presents a simple but accurate Finite Element Method (FEM) technique which is based on hexahedral parallelepiped finite elements and Whitney's edge basis functions. The technique is useful for the analysis of scattering from 1-D, 2-D, or from isolated 3-D scatterers. Numerical results are presented for a variety of such scatterers to show the usefulness of the method. The results also point to the need for the use of improved absorbing boundary conditions (ABCs) as well as of higher order basis functions when more accurate results are required. The emphasis in the proposed method is on its simplicity and versatility.

ISSN:0272-6343    

DOI:10.1080/02726349608908455

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The problem of determining a scattering potential from scattered field data is addressed within the Heitler equation. This equation relates the on shell components of the T matrix directly to the scattering potential. This relationship leads to a novel iterative reconstruction algorithm for recovering the distribution of the possibly complex index of refraction of the scattering potential from measurements of the scattered field outside the potential at, a single frequency. Reconstructions of cylindrical objects from data obtained in a suite of scattering experiments show that the method can handle relatively large objects compared to the wavelength whose index of refraction is close to the index of refraction of the surrounding medium.

ISSN:0272-6343    

DOI:10.1080/02726349608908456

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Interpolation of stochastic band-limited signals is of relevance both from the theoretical point of view and application purposes. It is well-known that the classical interpolation method for band-limited signals, which follows from the Whittaker-Kotel'nikov- Shannon sampling theorem, provides the appropriate answer to exactly reconstruct them. Unfortunately, whenever an open domain is in question, only truncated versions of cardinal series expansions can be employed and this generates artifacts on the interpolated data. In particular, the quality of the interpolation scheme affects the data statistics and is a relevant issue which must be carefully examined. An interpolation scheme, which minimizes statistical artifacts, is therefore of great interest. In this paper we propose the use of two efficient interpolation schemes and demonstrate that they provide much better results than the truncated cardinal series expansion.

ISSN:0272-6343    

DOI:10.1080/02726349608908457

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

This article discusses the generalized duality transformation in electromagnetics. The duality transformation affects material parameters in the bi-anisotropic constitutive relations. It will be shown that the two magnetoelectric phenomena, chirality and nonrecipro city, behave differently in the duality transformation. The analysis of the duality transformation is shown to be relevant to the question about the existence of non-reciprocal Tellegen media.

ISSN:0272-6343    

DOI:10.1080/02726349608908458

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The scattering problem of electromagnetic waves from a helicopter rotor is addressed in this work using the physical optics (PO) and physical theory of diffraction (PTD) equivalent currents techniques with quasi-stationary method. Experimental results indicated that, in the far zone, the field can be considered as harmonic and expressions for the spectral components of the field are obtained. The spectrum characteristics has a form similar to a frequency modulated lone modulation. Experimental results confirm the validity of the theoretical work.

ISSN:0272-6343    

DOI:10.1080/02726349608908459

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor